You sure? Cause even with the difference in lighting the eye on his burned side is much brighter than on the normal side. You eye color does not change that drastically by it being covered by a shadow.

They're both a greyish blue, and yes lighting can play a dramatic effect... my eyes change from brown to honey to green depending on my mood and lighting. You have to remember that the light is hitting his burnt side directly but not as much on his smooth side.